Impact of Ureteral Stenting on Urological Complications After Kidney Transplantation Surgery: A Single-Center Experience

BackgroundUrological complications such as ureteral strictures and ureteral leakage can affect the outcome of kidney transplantation by increasing morbidity and mortality, including graft loss. Controversy still exists regarding the role of stents in renal transplantation. The aim of this study was to evaluate the role of ureteral stenting in kidney transplantation.MethodsWe performed a retrospective study on a series of 798 consecutive renal transplants performed in our center between January 1, 2004, and December 31, 2011. Ureteral stents were used in 152 cases (19.1%) of the total (stent group) and were removed 2 weeks postoperatively. Donor and recipient age, sex, type of ureteroneocystostomy, stent and non-stent patients, cold and warm ischemia time, and urological complications were analyzed.ResultsThe overall incidence of urological complications was 7.8% (62 cases). Ureteral stenosis (3.1%) and ureteral leakage (2.4%) were the most common complications; 39.7% (25 cases) of complications were recorded in the first month after transplantation. Major urological complication rate was 3.3% in the stent group compared with 8.8% in the non-stent group (P = .04). However, stent use was associated with the increase of urinary tract infections rate in the stent group (51.3%) compared with the non-stent group (17.9%) (P = .03).ConclusionsIn our study, the use of ureteral stents significantly decreased urological complications in kidney transplant recipients but increased the risk for development of urinary tract infections.     

The effect of acetylcholine on renal haemodynamics

Acetylcholine (1 mg/min) was infused in 1 ml of physiological saline into the renal artery of dogs. 1) While arterial blood pressure was not significantly affected, renal vascular resistance decreased and renal blood flow increased by about 35%. 2) The increase in renal blood flow was not associated with an increase in C_PAH, whereas E_PAH diminished. 3) C_creat and E_creat decreased, while sodium and water excretion did not change significantly. 4) While in the control experiments the RBF measured on basis of the uptake of⁸⁶Rb was only 7% lower than the directly estimated renal blood flow (RBF_dir), the difference between the two values during the infusion of ACh increased to 40%. 5) The changes in response to ACh infusion have been accounted for by the opening of shunts and the inhibition of ionic transport across the tubular epithelium.     

Electrophysiological correlates of visual adaptation to faces and body parts in humans

The existence of facial aftereffects suggests that shape-selective mechanisms at the higher stages of visual object coding -- similarly to the early processing of low-level visual features -- are adaptively recalibrated. Our goal was to uncover the ERP correlates of shape-selective adaptation and to test whether it is also involved in the visual processing of human body parts. We found that prolonged adaptation to female hands -- similarly to adaptation to female faces -- biased the judgements about the subsequently presented hand test stimuli: they were perceived more masculine than in the control conditions. We also showed that these hand aftereffects are size and orientation invariant. However, no aftereffects were found when the adaptor and test stimuli belonged to different categories (i.e. face adaptor and hand test, or vice versa), suggesting that the underlying adaptation mechanisms are category-specific. In accordance with the behavioral results, both adaptation to faces and hands resulted in a strong and category-specific modulation -- reduced amplitude and increased latency -- of the N170 component of ERP responses. Our findings suggest that shape-selective adaptation is a general mechanism of visual object processing and its neural effects are primarily reflected in the N170 component of the ERP responses.     

Die Blutströmung und PAH-Extraktion der isolierten Niere in der osmotischen Diurese und unter Ureterverschluß

Zusammenfassung An isolierten, perfundierten Hundenieren wurden Experimente zur Untersuchung der Nierendurchblutung und PAH-Extraktion in osmotischer Diurese und unter Ureterverschluß durchgeführt. Die Bestimmung der Nierendurchströmung erfolgte simultan aufgrund des vernösen Abflusses (direkter RBF-Wert) und nach der Rb-Methode (Rb-RBF), die der regionalen Nierendurchströmung aufgrund des Rb-Gehaltes in der Rinde sowie im äußeren und inneren Mark. Während des freien Harnabflusses betrug der direkte RBF-Wert durchschnittlich 413 ml/min/100 g, der Rb-RBF-Wert durchschnittlich 310 ml/min/100 g, der Quotient der Rinden-Rb-Blutströmung und der totalen Nierendurchblutung im Durchschnitt 0,64 und die PAH-Extraktion durchschnittlich 0,63. Unter Ureterverschluß sank der direkte RBF-Wert auf durchschnittlich 307, der Rb-RBF-Wert auf durchschnittlich 181 ml/min/100 g, der Quotient der Rinden-Rb-Blutströmung und totalen Nierendurchblutung auf durchschnittlich 0,51, die PAH-Extraktion im Durchschnitt auf 0,52.Die auch schon bei den Kontrollperioden nachweisbare Differenz zwischen dem direkten und dem Rb-RBF-Wert wird im Einklang mit der entsprechend niedrigeren PAH-Extraktion auf die in der isolierten Niere auch bereits bei freiem Harnabfluß bestehenden offenen AV-Shunts zurückgeführt. Während bei der Niere in situ die Steigerung des postcapillaren Widerstands unter Ureterverschluß durch die Öffnung von AV-Shunts kompensiert werden kann, nimmt durch das Fehlen dieses Kompensationsmechanismus in der isolierten Niere unter Ureterverschluß der totale Nierenwiderstand zu und sowohl die capillare als auch die totale Durchblutung der Niere ab.     

Adaptation duration affects the spatial selectivity of facial aftereffects

Adaptation processes in human early visual cortical areas are sensitive to the exposure time of the adaptor stimulus. Here we investigated the effect of adaptation duration at the higher, shape-specific stages of visual processing using facial adaptation. It was found that long-term (5s) adaptation evokes facial aftereffects consisting of a position invariant as well as a position-specific component. As a result of adaptation to a female face, test faces were judged more masculine when they were displayed in the same location as the female adaptor face, as compared to that when they were presented in the opposite visual hemifield. However, aftereffects evoked by short-term (500 ms) adaptation were found to be entirely position invariant. In accordance with these behavioral results, we found that the adaptation effects, measured on the amplitude of the N170 ERP component consisted of a position-specific component only after long-term, but not after short-term adaptation conditions. These results suggest that both short and long exposure to a face stimulus leads to adaptation of position invariant face-selective processes, whereas adaptation of position-specific neural mechanisms of face processing requires long-term adaptation. Our findings imply that manipulating adaptation duration provides an opportunity to specifically adapt different neural processes of shape-specific coding and to investigate their stimulus selectivity.     

Comparative Urologic Complications of Ureteroneocystostomy in Kidney Transplantation: Transvesical Leadbetter-Politano Versus Extravesical Lich-Gregoir Technique

Background

The incidence of urologic complications after kidney transplantation remains high despite improvements in diagnosis and operative techniques. Urinary tract reconstruction is usually done by ureteroneocystostomy (UCNS), and several techniques are available. In this study, we evaluated the outcomes of 2 different UCNS techniques performed in our department, the transvesical Leadbetter-Politano (L-P) and the extravesical Lich-Gregoire (L-G) technique.

Material and Methods

We evaluated the outcomes of 2 different UCNS techniques, L-P versus L-G, performed in our department between July 1, 2006, and December 31, 2011. During this period, we performed 524 consecutive renal transplantations—264 cases using the L-P technique (50.3%) and 260 cases with L-G technique (49.7%). Renal grafts were obtained from cadaveric donors in 146 cases (27.86%) and from living-related donors in 378 cases (72.14%). Recipient mean age was 35.64 years and the male to female ratio was 1.63:1.

Results

Urologic complications after kidney transplantation occurred in 22 cases in the L-P UCNS group (8.33%). The most common complications were ureteral stenosis (3.41%) and leakage (2.65%). Other complications recorded were lymphoceles (1.89%) and hematoma with secondary ureteral obstruction (0.38%). Compared with the L-P UCNS technique, the L-G technique was associated with fewer overall complications (6.15% vs 8.33%; P = .06), a lesser rate of ureteral stenosis (2.31% vs 3.41%; P = .08), and a similar rate of leakage. However, statistical analysis revealed no differences between the 2 techniques (P = .06). In addition, we did not note any differences in graft and patient survival between the 2 groups.

Conclusions

In our study, the extravesical L-G technique has a lower complication rate compared with transvesical L-P procedure, but without statistical differences. Furthermore, the L-G technique is easier and faster to perform, it avoids a separate cystotomy, and requires a shorter ureteral length. In conclusion, we recommend L-G technique as technique of choice in kidney transplantation.     

The enhancement of cortical excitability over the DLPFC before and during training impairs categorization in the prototype distortion task

The present study investigated the effects of transcranial weak electrical stimulation techniques applied to the right and left dorsolateral prefrontal cortex (DLPFC) on categorization learning measured using a variant of the prototype distortion task.During the training phase of this task subjects saw low- and high distortions of a prototype dot-pattern. 60 participants received 10 min of either anodal or cathodal transcranial direct current (tDCS), transcranial random noise (tRNS) or sham stimulation before and during the training. We have assessed the effects of the intervention during a test phase, where the subjects had to decide whether the consecutive high- and low-distortion versions of the prototype or random patterns that were presented belonged to the category established in the training phase.Our results show that the categorization of prototypes is significantly impaired by the application of anodal tDCS and tRNS to the DLPFC. The prototype-effect, observable in the case of the sham stimulation group, was severed in all active stimulation conditions.